1. Field of the Invention
This invention relates to a detecting method for a touch panel.
2. Description of the Prior Art
Flat display devices have become the mainstream in various types of display devices. For instance, the home televisions, monitors of personal computers and laptop computers, mobile phones, and display cameras are electronic products which extensively incorporate the flat display devices. As product design is driven toward user friendliness, thus display panels having touch input function are gradually becoming a key aspect in the development of flat display device industry.
Conventional touch panel technologies include resistive type, capacitive type and optical type touch panels. As for the resistive touch panels, the working principle is to determine a touch point by detecting voltage drops on the touch panel. The resistive touch panel includes two conductive layers separated by a narrow gap and a voltage difference exists between the two layers. When an object touches a point on the touch panel, the two layers become connected at that point and a conduction loop is created at the touch point. The conduction loop creates a voltage drop for the system to recognize and determine the position of touch point. However, the resistive touch panel cannot process multiple touch inputs or perform fingerprint recognition. Furthermore, the user needs to apply certain amount of pressure on the touch point to create a conduction loop, thus the resistive touch panel is subjected to the limitation of minimum applied force.
The working principles of the capacitive touch panel and the optical touch panel are different from that of the resistive touch panel, because both touch panels can process multiple touch inputs. In general, the capacitive or optical touch panel scans all sensing units of the touch panel in one frame period to obtain data and then store the data. Afterward a gradient image processing algorithm is employed to determine the number and positions of the objects touching the panel. However, the gradient image processing method is slow and requires a large amount of storage space which in turn decreases the overall system efficiency.